Oh Canada, our home and chilly land….

Do you have employees working outdoors? Have you considered the effects of cold stress on these workers? Canadian and American initiatives have resulted in guidelines that can help employers protect workers from cold stress.

The “Wind Chill”. The “dry bulb” temperature (what we typically read on the thermometer outside in the shade) and wind speed can be used to calculate a “Wind Chill” temperature. The Wind Chill index was developed jointly by the USA and Canadian Weather Services. It is only used when air temperatures drop below 5°C and wind speeds are 5 km/h or greater. This index considers the impact on exposed flesh. For example, an air temperature of 4°C with winds of 64 km/h, feels more like -12°C. A worker exposed to these conditions is at low risk of his/her skin freezing if working in these conditions for less than an hour. However, an employee exposed to a air temperature of -18°C and a wind speed of 35 km/hour, will experience a wind chill that feels like -35°C. This worker would be at great risk of exposed skin freezing within 1 minute of exposure.

Work Warm up Schedule. The American Congress of Governmental Industrial Hygienists developed guidelines that we use in the summer for HEAT stress. They also adopted a “Work Warm-Up Schedule” that was originally developed by the Saskatchewan Department of Labour (a Canadian invention!!). You can find Saskatchewan’s guidelines at http://www.lrws.gov.sk.ca/cold-condition-guidelines-working-outside. CCHOS’s web page also includes these guidelines at http://www.ccohs.ca/oshanswers/phys_agents/hot_cold.html?print.

Here is an example of how this guideline works. At an air temperature of -27°C, with a 16 km/h wind (enough to “fully extend a flag”), workers should work no more than 75 minutes, followed by 10 minute warm-up break. They would need 2 warm-up breaks every 4 hours. The chart assumes that the worker has moderate physical activity (e.g. a construction worker). A worker who has to stand still in these conditions (e.g. a parking attendant) would need a warm-up break every 55 minutes.

If your company has workers out in the cold, consider these control measures for cold stress, in addition to the work warm-up breaks described above:
• Use wind breaks or tents to isolate the worker from wind
• Encourage job rotation between “cool” and “warm” work
• Provide “warm” areas for breaks
• Encourage workers to change from wet to dry clothing
• Use portable radiant heaters
• Provide heating vests or packs
• Provide appropriate PPE for working in the cold
• Use insulating materials on handles to prevent contact with cold objects with bare hands
• Encourage workers to stay well-hydrated and well-fed
• Educate workers on the signs and symptoms of cold stress

Bundle up, and enjoy our great Canadian weather!

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